You cannot read this installment without having read the previous books first. That's for sure. This one started directly after [b:Lesser Evils|16006803|Lesser Evils (Infected, #6)|Andrea Speed|https://d.gr-assets.com/books/1347571996s/16006803.jpg|21771954] ended; and here we saw more of Holden in actions, the weirdly macho hockey teams, and Dylan showing a bit of his teeth!!
Of Roan, besides the actions and superhero antics, we saw more inner turmoil, drama (yep, he's a bit of drama queen too :p), and despite the beast inside of him, more human.
Being a late comer (reader) and as there are already so many praises on this, I'd just add my two-cents here:
If you haven't started reading this series, do it now, highly recommended!